We're working on releasing a similar "slipstream" version of
SharePoint Server SP1 which will include both the full version of WSS
the WSS SP1 patch, SharePoint Server 2007 full version including
the SP1. The installation will automatically include the service
pack. In the mean time I recommend you look at Ben Curry's (SharePoint
MVP) post on installing SharePoint Server 2007 on RC1
(instructions include how to put SP1 in the update). You'll hear about
the download here when it's available. Martin Kearn has some similar instructions for including the WSS SP1 and MOSS SP1 when installing on Windows Server 2008.
Note, when installing SharePoint Server 2007 on Windows Server 2008 it
does require both WSS SP1 and MOSS SP1 be included when you install.

Upgrading from Windows Server 2003 to Windows Server 2008

After release you'll see more instructions on this topic on
TechNet. We don't recommend you upgrade production environments until
after the Windows Server 2008 release. We announced that this
release was the last 32-bit version of SharePoint Products and
Technologies at Tech Ed IT Forum 2007. I was exited to hear Steve
Smith (SharePoint MVP) and Penny Coventry (SharePoint MVP) both of Combined Knowledge, have just released a paper on How to move a SharePoint Server 2007 32-bit environment to a 64-bit environment on Windows Server 2008. What a great document to get familiar with and to start including this in your plans.

SharePoint will have a booth at the Windows Server 2008 launch event
in Los Angeles. We'll have copies of the new SharePoint Deployment
Essentials guides. We hope to see you there.

If you're trying to find more resources on Windows Server 2008, I recommend reading up...

The SQL 2008 team and the SharePoint Team are working together to
make both products better and to ensure a better together experience.
We currently plan to support SQL 2008 at its release. Expect to hear
more about this as well. We don't recommend running production
SharePoint environments on SQL 2008 with pre-release (CTP) builds.